"You know, over the years I have used aliases...I used the name Barron and made a very good deal using that name," he said, adding that it became the inspiration for the name of his own son, Barron Trump.

Despite this, two weeks ago Mr Trump denied ever using aliases during a TV interview where he was confronted with an audio recording of an apparent Trump publicist named "John Miller" whose voice sounded remarkably similar to his own.

"To me that didn't sound like my voice," he said and denied that he was infamous for impersonating his own press officers and publicists when speaking to reporters in New York in the 1980s.

In the bizarre audio recording, uncovered by the Washington Post, "John Miller" praises Trump as "a good guy [who] is not going to hurt anybody" and speaks at length about his great business acumen.

"Miller" even goes on to suggest that the singer Madonna "wanted to go out with" Mr Trump, as well as claiming that "important, beautiful women call him all the time."

The cadence, tone and choices of phrase used by "Miller" are all strikingly similar to Mr Trump's own manners of speech.

The admission comes a day after violent protesters outside a Trump rally threw burning items at police and toppled barricades, Trump's afternoon rally in Anaheim was boisterous but less heated.

Outside, demonstrators quietly held up signs reading "Love and Peace" and "Migration is beautiful" during the rally, but the modest crowd grew rowdier when Trump supporters came outside. The two sides shouted at each other as dozens of police, some on horseback, moved in to prevent a renewal of the violence Tuesday night in New Mexico.

Five people were arrested as a line of police slowly moved scattered protesters along a nearby street.

Inside, Trump's rally was interrupted several times by protesters who were escorted out of the Anaheim Convention Center.